1. Field of the Invention
The invention relates to a centrifuge for separation and/or treatment of blood or blood components, comprising a rotor having a central compartment and an annular separation compartment, which are arranged concentrically with the axis of rotation of the rotor and are adapted to accommodate a container system comprising a round bag and one or more secondary containers connected thereto, the separation compartment being adapted to accommodate the round bag and the central compartment being adapted to accommodate the secondary containers, and the centrifuge further comprising means for reducing, in operation, the volume of the separation compartment in order to displace a separated fraction from the round bag to a secondary container in the central compartment.
The invention also relates to a container system to be arranged in the centrifuge according to the invention.
2. Description of the Related Art
By round bag is below meant an essentially annular flexible container, which can be produced, for instance, by welding together superimposed plastic films along an outer annular edge and an inner annular edge. The annular container can, in the same way as described in WO 95/01842, be cut off and the thus-formed opposite ends sealed. These opposite ends are arranged in an overlapping manner when the round bag is mounted in the centrifuge or on a cassette, thereby giving the round bag the shape of a truncated cone.
U.S. Pat. No. 5,114,396 discloses a method and a container system for washing blood cells by using a centrifuge of the type mentioned by way of introduction. In this prior-art container system, use is made of the central part inside the round bag as a secondary container, and a continuous unit is obtained, which essentially is oriented in a horizontal plane. When large volumes of liquid are to be handled in the secondary containers, this container system requires a large rotor diameter. International Patent Application WO 95/01842 discloses a container system which in a corresponding manner utilises the central part inside the round bag as a secondary container. In this case, the round bag is shortened by letting two opposite sealed ends of the ring overlap in connection with the mounting of the round bag on a rigid centre part, thereby obtaining the shape of a truncated cone. The secondary container is pressed into a cavity in the rigid centre part. The cavity has a smaller diameter than the secondary container, and its radially outer parts are folded along the walls of the cavity. In this way, the entire system obtains a small diameter and can be accommodated in a correspondingly small rotor. Especially when separating sensitive cell suspensions, e.g. platelets, this system has great advantages since the separation must be effected with a certain amount of caution and the cell suspension is not allowed to be exposed to high G fields for long periods. However, the system is suited above all for separations where the secondary containers are initially empty and can easily be mounted in a deformed state in the cavity.
An object of the present invention is to provide a centrifuge of the type mentioned by way of introduction, which has a compact size and can easily be used for various types of separations by means of different container systems in the form of cassettes. Thus, the centrifuge can be used for separations and treatments where large amounts of liquid are to be handled in secondary containers, for instance in connection with the washing of cells, as well as for separations of the type described in WO 95/01842. Further objects and advantages of the invention will be apparent from the following specification.
The inventive centrifuge is characterised in that the central compartment is a tubular shaft cavity in the centre of the rotor, and that the annular separation compartment is arranged around the cavity at the upper part thereof.
By this design of the rotor, large volumes of liquid in secondary containers can be held in the central compartment and the diameter of the rotor can still be made relatively small. The rotor obtains good balance by the placing of the liquids in the shaft cavity close to the axis of rotation of the rotor. Preferably the separation compartment has a conical shape and is inclined obliquely downwards or obliquely upwards, which further reduces the diameter of the rotor and expedites the separation through the inclined separation compartment.
The rotor is adapted to accommodate a container system comprising a tubular sleeve which is adapted to the shaft cavity of the rotor and on which the round bag is mounted and in which the secondary container/containers are arranged.
A first container system according to the invention, for separation and/or treatment of blood or blood components, adapted to placed in the centrifuge, is characterised by a round bag which has an outer annular edge and an inner annular edge; two or more flexible secondary containers, of which at least one contains a treatment liquid; a tube system connecting the round bag with the secondary containers; a tubular sleeve which is adapted to the shaft cavity of the rotor and which is adapted to accommodate the secondary containers standing side by side and resting against each other, and which at its upper part comprises a projecting flange, and in that the round bag, by means of its inner edge, is adapted to be mounted on said flange.
This container system is in the first place intended for separations and treatments comprising the handling of relatively large volumes of liquid in the secondary containers, for instance, when washing blood cells. In washing, use is made of one or more secondary containers containing washing liquid (washing liquid container) and an initially empty secondary container (waste liquid container) which is adapted to receive waste liquid which is displaced from the round bag after a completed washing step. The total volume of liquid in the secondary containers may constitute 2-3 liters. Thanks to the flexible secondary containers which rest against each other, the space is maximally utilised. In the course of the process, the volume of washing liquid in the washing liquid container decreases and increases to the same extent in the waste liquid container.
The container system is also suited for other types of separations and treatments which involve liquids in secondary containers, for instance, treating, reconditioning and preserving liquids, which at some stage of the process are transferred to other bags in the system to be mixed with a blood component therein. Even if use is not made of all bags during the actual centrifugation process, they must be loaded into the centrifuge since the containers normally constitute an interconnected sterile unit that should not be disconnected and be connected again.
A second container system according to the invention to be inserted in the centrifuge is characterised by a round bag having an outer annular edge and an inner annular edge; a secondary container; a tube connecting the round bag with the secondary container; a tubular sleeve which is adapted to accommodate the secondary container and which has a smaller diameter than the shaft cavity of the rotor and on its outside has support elements which are adapted to engage the walls of the cavity and centre the sleeve in the centre of the cavity, and at its upper part has a projecting flange, and in that the round bag by means of its inner edge is adapted to be mounted on said flange.
This container system makes it possible to use the same centrifuge also when relatively small volumes of liquid are to be handled in a secondary container in the central shaft cavity of the rotor, for instance, when only one initially empty container is arranged in the sleeve to receive a separated component from the round bag while the centrifugation proceeds.